Single side band amplifier circuit



A g- 1940. w. H. WlRKLER SINGLE SIDE BAND AMPLIFIER CIRCUIT INVENTOR.

Original Filed Aug. 4, 1938 ATTORNEY ciple in splitting double side band currents into Patented Aug. 13, 1940 smear: smn BAND amm'rna-cmcurr Walter H. Wirkler,

to Collins Radio Company,

Cedar Rapids, Iowa, assignor Cedar Rapids,

' Iowa, a corporation of'lowa Origina 4 Claims.

" My invention relates broadly to an amplification system for single side band waves, and more particularly to a split side band amplifier having means for dissipating undesired side bands. The

circuit of my invention is applicable in single side band suppressed carrier transmission systems of the type shown in my copending application I Serial No. 176,670, filed November 26, 1937, Patent No. 2,173,145, September 19, 1939, for Single side band transmitter. 1

This application is'a division'of my copending application Serial No. 223,096, filed August-4,

1938, for Split side band amplifier circuit.

Oneof the objects of my invention is to provide means forthe selection and efhcient ampli- 'fication of single side band currents, with the carrier suppressed. 1

Another object of my invention is to provide an amplification system for split side band circuits adapted for single side band systems.

Still another object of my invention is the provision of means for using the bridge circuit printwo single side band currents.

A further object of my invention is to provide a balanced bridge circuit for deriving single side band currents from sets of double side band components in phase quadrature, for transmission exclusive of the other side band component.

Other and further objects of my invention reside in the circuit arrangement herein disclosed and hereinafter more fully described with refer- I ence to the accompanying drawing which'schematically' illustrates one form of my invention. 7 The circuit arrangement is generally similar a to the corresponding portion of the single side Serial -No. 176,670, above noted, 1

The drawing shows the modulationland side ns my ,tion; The source of carrier energy at I includes waves in the 'diflerent an oscillator .and amplifier and the carrier energy is "red on the one hand through phase shifting network 2 to balanced. modulator 22, and antheother hand directly .to balanced modulator 23, the

waves in the diflerent modulators being in phase "quadrature. The source of signal-modulations, such as a program line at l2, delivers modulation energy tojthe balanced modulators-'22 and 22:

through phase shifting networks. I and 6 and amplifiers and 2 I respectively, the modulation of phase, The carrier energy is suppressed in the balanced modulators and double side bands-are present in the outputs thereof, 90 out of phase' ferred embodiment, I do in the separate circuits. 4

The modulators are of the type shown in application Serial No. 176,670, with carrier and modulation ener y impressed in push-pull rela- 1 application August 4;,

Divided and this tember 16, 1939, Serial No.

modulator -22, and V1:

' bridge circuit 29.

I outputs thereof are, respectively: band. transmitter of 'my copending applicationband amplifier portions of a transmitter embody-- invention of single sideband amplifica- 'to amplifierthe components injshe modulators-Being 90 out 1938, Serial No. application Sep- 295,311 7 tion on the grids or the tubes, v, and V1: in

Blocking condensers C1: and radio frequency choke coils Ho are provided in the grid circuits. as I indicated, and grid bias in the modulators is supplied from sources D: and D4 as shown. By the application of the bridge circuit of my and V14 in modulator 23.

invention to the combination of the double side band waves in the outputsof both modulators 22 and 23, interaction. or cross modulation in the two circuits is prevented. The plate electrodes in the tubes in each balanced modulator are .con-

nected together and to the respective load circuit, 24 or 25, thence in common to the source of plate power Go, through radio frequency choke coils H1: The load circuits 24 and 25 are inductively coupled to opposite diagonal terminals of Two arms of the bridge are formed by capacitances' C13 and C14, 9. third by the load presented by the at 21, andthe fourth by a resistor 28 which operates to dissipate the undesired side bands. Amplifier 21 receives the superior or the inferior side bands from both balanced modulators 22 and 23, depending upon' whether the outputs of the modulators are subtracted or added in the arm of thebridge comp ing the input circuit of the amplifier 21. The bridge circuit" is balanced so that no interaction between the: balanced modulators 22, 22,-can occur. The single side band thus derived andamplified at 21 is fed to the antenna system for radiation. j

The theory of operation of the bridge-circuit is as follows. Because of thedliferencein carrier excitation phase-for modulators 22 and 22,the

In are split into two portions the components in the input 21 being-added, for example, while. resistor 22 are subtracted.

Thedurrents L and in bridgecircuit 26,

thus: I I

A (ua-g) =I and I I p fri -+P where n indicates the inferior side mea s I. the superior side band.

While I' have disclosed Specifically thereto, and it is to be understood of the appendedclalms.

class B linear amplifier myinventioninaprv not intend to belimited What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. Asplit side band amplifier including a bridge circuit, means for supplying said bridge circuit at both pairs of opposite terminals with double side band energy, carrier and modulation factors in said double side band energy at the pairs of opposite terminals being respectively in phase quadrature, with adjacent arms of said bridge carrying inferior and superior side band components respectively, an amplifier connected with one arm of said bridge for amplifying the single side band component therein, and means connected in an arm of said bridge adjacent the aforesaid arm for dissipating energy of the other side band component.

2. A split side band amplifier including a bridge circuit, means for supplying said bridge circuit at both pairs of opposite terminals with double side band energy, carrier and modulation factors in said double side band energy at the pairs of i opposite terminals being respectively in phase quadrature, with adjacent arms of said bridge carrying inferior and superior side band com ponents respectively, an amplifier connected with one arm of said bridge for amplifying the'single side band component therein, and a resistor connected in an arm of said bridge adjacent the aforesaid arm for dissipating energy of the other side band component. a

3. A split side band system including a bridge circuit, means for supplying said bridge circuit at both pairs of opposite terminals with double side band energy, with carrier and modulation factors respectively in phase quadrature, the double side band energy in arms of said bridge circuit being additive and subtractive respectively, resulting in the former instance in inferior side band components and in the latter in superior side band components, of like phase: amplifier means connected in one arm of said bridge circuit for amplifying the single side band components in the output thereof, and a resistor connected in an adjacent arm of said bridge circuit for balancing said circuit and dissipating energy of the other side band components therein.

4. A split side band amplifier including a bridge circuit, means for supplying said bridge circuit at both pairs of opposite terminals with double side band energy, carrier and modulation factors in said double side band energy at the pairs of opposite terminals being respectively in phase quadrature, said energy being additive in opposite arms of the bridge and resulting in inferior side band currents in said opposite arms, said energy being subtractive in the alternate opposite arms of the bridge and resulting in superior side band currents in said alternate opposite arms, one arm 01' said bridge having amplifier means connected therewith for amplifying the single side band currents therein, and an adjacent arm of said bridge having energy dissipating means connected therewith for suppressing the single side band currents therein.

WALTER 1r. wmKLER. 

